Research output: Chapter in Book/Report/Conference proceedingConference contribution


The goal of this presentation is two-fold: The primary goal is to present my view of cochlear function as revieled by DPOAE experiments. To understanding of how the cochlea works one must understand the functional roles of the basilar (BM) and outer hair cells (OHC). A great deal of progress has been made in the last 50 years. Conclusions: The use of nonlinear (NL) distortion product generation has revealed a deep understanding of cochlear function. The most important, and surprising result, is that the cochlea may be approximated as a linear system having level dependent properties, first proposed by deBoer as the “EQ-NL theorem.” When the suppressor frequency fs is at least 1/2 octave lower than the characteristic (“best”) frequency (fcf ), it is best known as “low-side” suppression. There is no “low-side” suppression for suppressors below 65 [dB-SPL] [1]. For suppressors above 65 [dB-SPL], suppression is engaged, with a slope between 1-2 [dB/dB].[2] Since the excitation threshold is also 65 [dB-SPL], we conclude that the neural threshold of excitation to both the inner and outer hair cells have nearly the same threshold. That is the suppression threshold of the OHC are nearly equal to, the IHC threshold. This raises the interesting question: If the IHC and OHC 65 [dB] thresholds are the same in the tails of the tuning curves, how can the CA function at threshold levels? Furthermore this is a highly unexpected result because low-side suppression, as measured on the basilar membrane, has a 20-30 [dB] higher threshold [3, 4]. Is the OHC action restricted to the neighborhood of the neuron's best frequency? This would require that the neural low-side suppression and loudness recruitment (the reduced loudness of low-intensity sounds in the hearing-impaired ear) are closely related (i.e., are the same phenomena). The ramifications of this observation seem significant as they must impact our fundamental understanding of hearing and thus hearing loss (p. 332, Allen90) [5]. In summary: Two-tone suppression acts like an automatic gain control, compressing the loudness dynamic range, thus expanding the range of hearning, with little audible distortion.

Original languageEnglish (US)
Title of host publicationProceedings of the 29th International Congress on Sound and Vibration, ICSV 2023
EditorsEleonora Carletti
PublisherSociety of Acoustics
ISBN (Electronic)9788011034238
StatePublished - 2023
Event29th International Congress on Sound and Vibration, ICSV 2023 - Prague, Czech Republic
Duration: Jul 9 2023Jul 13 2023

Publication series

NameProceedings of the International Congress on Sound and Vibration
ISSN (Electronic)2329-3675


Conference29th International Congress on Sound and Vibration, ICSV 2023
Country/TerritoryCzech Republic

ASJC Scopus subject areas

  • Acoustics and Ultrasonics


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